NYT: Senator Barack Obama of Illinois, standing before the Old State Capitol where Abraham Lincoln began his political career, announced his candidacy for the White House on Saturday by presenting himself as an agent of generational change who could transform a government hobbled by cynicism, petty corruption and “a smallness of our politics.”

…. It was the latest step in a journey rich with historic possibilities and symbolism. Thousands of people packed the town square to witness it, shivering in the single-digit frostiness until Mr. Obama appeared, trailed by his wife, Michelle, and two young daughters….

…. The formal entry to the race framed a challenge that would seem daunting to even the most talented politician: whether Mr. Obama, with all his strengths and limitations, can win in a field dominated by Senator Hillary Rodham Clinton, who brings years of experience in presidential politics, a command of policy and political history, and an extraordinarily battle-tested network of fund-raisers and advisers.

…. “If a campaign is premised on personality, then no, I don’t think you can stay fresh for a year,” he said. “But if the campaign is built from the ground up and there is a sense of ownership among people who want to see significant change, then absolutely. It can build and grow.”